Saturday, 14 February 2015

Scored myself a full day in the shed on Friday before last thanks to the Waitangi Day public holiday here in NZ. My girlfriend had to work (poor thing) and the weather was dreadful in Dunedin. Basically, conditions were ideal for an uninterrupted, guilt-free geek-out!

To set the scene, I scored these two New Zealand flavoured cabs from Trade Me back at the start of December 2014. I paid a measly NZD $25 for both! The owner had planned to restore them but decided to abort the project. The lot didn't include monitors or game boards but it did include control panels, marquees, glass panels and a couple arcade power supplies:

Two gutted Coin Cascade cabinets

So, the mission since then has been to find a some CRTs that would fit the monitor cutouts...

After wasting some time trying to work out why WinModelines wouldn't let me set C-Sync for on my laptop anymore, I decided to try an upgrade to my RGB insertion hack I'd been planning for a while. I wanted to see if I could get the Jungle IC in my TV to accept the composite sync signal directly instead of feeding it in via the RCA video input. The idea was that if I could get sync direct to the video chip, there'd be no need to switch to the AV channel in order to have the RGB signal sync.

RGB and C-Sync direct injection to the video processor IC

Along with the RGB and blanking pins on the Jungle IC, there are pins for an external CVBS sync input and also a voltage controlled AV input switch. After mapping out a place to patch into using my multimeter, I wired up a LM317 voltage regulator to produce a steady 8 volts.

Control voltages and RGB interfacing

After soldering it all up, I flicked the power to the chassis and it worked first pop! Excellent! This means the TV can now function as a dedicated RGB monitor. No need to switch the AV input. This is perfect for cabinet use since you don't have to do anything get the monitor to show RGB. It's just like a real arcade monitor!

Panasonic A48KXR98X tube

Philips chassis mounted in cab

Exton RGB 201 RXi for composite sync and level adjustment

So, how does the image quality of a $5 Philip 20PT138A TV with an RGB hack stack up against a SCART television or arcade monitor? Judge for yourself...

Final Fight title screen

Final Fight in game

After (quickly) hooking up an iPAC (the most expensive part of this project by far) I was finally able to play a game on a real-life cab (woohoo!). Once I replaced the fluorescent tube behind the marquee things really started to nail the vibe...

Dangling iPAC

Try This One!

Of course, there are a hundred things I still need to do before I call the project finished (speakers, dedicated PC, new microswitches, cosmetic clean-up, etc.) but I'm pretty stoked with the result!

Looking forward to mounting a vertical monitor in the other cab... should cover many bases.

In between all this, of course, I have collected a bunch of CRTs and gadgets. I even have myself a couple gutted arcade cabinets that were from an arcade in my new hometown (Dunedin, New Zealand.)

Before we talk about any of that cool stuff, I want to show off my latest project... adding an RGB input to a non-SCART television! The thing that drove me to delve into this is fact that my cabs need a couple 21 inch monitors... and the combination of RGB to YUV converter I bought and component television I tried just didn't do it for me.

Now, before we get to the glorious RGB money shots, I need to say a big thank you to 133 MHz and Tim Worthington. Without their expertise and willingness to share their knowledge, there's no way I would have ever pulled this off (or even thought to do it in the first place). I'll post an entry of all the necessary links soon but, in the moment, let's take a quick tour:

As well as all this 15 kHz progressive resolution glory, interlaced modes work just fine too!

Dead Or Alive ++ (Japan)Tecmo, 1998640 × 480 @ 60.000000 Hz

Thanks to a handy vertical size pot, this TV can also be quickly adjusted for 256 line games!

R-Type IIIrem, 1989384 × 256 @ 55.017606 Hz

I have to say the this Sanyo tube performs very nicely. Check this zoom-in:

Close-up

This is an extremely exciting development! This changes the nature of my CRT pursuit considerably! No longer am I restricted to the SCART option when it comes to RGB monitors!

There's a lot more detail to discuss with all this... and I'm hoping to write a generalised step-by-step guide for this modification.

In the meantime, I can report that my success was not limited to this one television. Check out this nice 20 inch Philips radiating new-found RGB goodness:

20 inch Philips with a similar Jungle IC

Amazingly, the second TV only took about 30 mins to modify. I didn't even have the proper schematic for this TV! Knowing what the pins on the TDA jungle chip do, I was able to pinout the RGB and blanking lines using a digital multimeter. Then, I simply changed over my breakout cable from the Sanyo to the Philips. Flicked the power switch and saw the above RGB picture 3 seconds later! Amazing!

To be honest, weeks of reading and research have gone into this. But now I know how, recreating this mod would be faster than soldering a VGA to SCART cable. And the results are better for several reasons (that I'll explain in the future).

For the moment though, the dream of cheap and abundant arcade replacement monitors has become a reality!